Core box vent plug



Nov. 10, 1936. c, R s E 2,060,350

CORE BOX VENT PLUG Filed May 18, 1956 INVENTOR.

CARL H. SILEE Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE Application May 18,

1 Claim.

This invention relates to the apparatus for and the production of molds andcores and in more particular to vents permitting the escape of the air entrapped by the sand usually supplied under 5 a high pressure.

Without the, use of vents in the walls of the forms used in the production of sand cores and sand molds, the entrapped air may cause soft spots or voids in the sand core or mold as the case may be, resulting in imperfect castings or molded articles. Various types of vents have been tried in the past; but due to the materials used and the design of the vents, these have not been as dependable as desired. It has been a common practice to provide a cup-shaped plug made from brass, the bottom or end of which is provided with several fine holes, sufficiently fine to retain the sand, but theoretically permitting the escape of air. Due to the thickness of the material used and due to the fact brass, especially when corroded, seems to adhere to sand, the fine apertures become clogged, thereby defeating the operation thereof.

An object of this invention is to provide a vent unit that is easily manufactured, that has sufficient rigidity to withstand the impact of the approaching sand, that is cheap, efficient and dependable.

Another object of this invention is the use of n materials to which sand does not adhere.

Other objects and advantages reside in the construction of parts, the combination thereof and the mode of operation, as will become more apparent from the following description.

Fig. 1 is a perspective View of the vent unit ready for insertion in the form for producing sand cores or molds or the like.

Fig. 2 is a schematic view of a core box placed in position in a suitable machine or apparatus for filling the core box with sand under pressure, the core box being provided with suitable air escape units allowing the entrapped air to escape.

Fig. 3 is a perspective view of the foraminous diaphragm in readiness to be inserted into a shell shown in section.

Fig. 4 is a sectional view of a portion of an apparatus having the parts of the air escape unit in readiness for the forming operation.

Fig. 5 shows the parts shown in Fig. 4 after the forming operation has been completed.

Referring to the drawing the reference character I indicates the walls of a form having a cavity l2 that may be filled with sand or other granulated material to form a core to be used in molding- The forms l0 may be mounted upon 1936, Serial N01. 80,403

a suitable support I4 and filled with sand under pressure supplied from a container I6, having an orifice l8 that is controlled by a suitable valve not shown for supplying the sand 20 to the cavity l2. Before beginning to fill the cavity I 2 it is normally filled with air. Likewise a certain amount of air used in forcing the sand 20 into the cavity l2 will also enter the same, which would cause pockets or soft spots to be formed in the sand core in the absence of vents or air escapes.

In order to permit the air to escape from the cavity I2, suitable. vent areas 22 may be inserted at strategic points in the wall In of the core box. The location of the vents or air escapes is dependent entirely upon the shape of the core or the mold as the case may be and the judgment of the maker of the mold.

In order to prevent escape of the sand through the openings in the walls of the core box or form, a suitable foraminous diaphragm 24 supported in a cylindrical sleeve 2-6 is fixedly mounted in the W s o t e r b or mold, t m y b hel in position by a press fit operation.

The diaphragm 24 may consist of a Monel metal screen of a suitable mesh to retain the sand; but permit a free escape of air. This screen is seated upon an annular shoulder 28 adjacent one end of the tubular sleeve 26 and held in position by a flange or lip 30 that may be crimped by a suitable mechanism, so as to overlap the edge of the screen to rigidly hold it in position.

As may best be seen by referring to Figs. 3, 4 and 5, the screen engaging surface is disposed at a slight angle, so as to better grip the edge of the screen. This inclined surface has another decided advantage. The annular screened discs 24 are preferably cut by a suitable die or punch from a screen sheet and as the screen is stamped it is dished or curved slightly, similar to the section shown in Fig. 4. The inclined surface receiving the screen is preferably selected at such an angle as to coincide with the curvature of the screen.

The screen disc 24 and the sleeve 26 are preferably placed upon a suitable matrix 32 in readiness for the forming operation which is accomplished by advancing the ram 34 against the end of the matrix 32. The ram 34 is provided with a disc cavity 36 shaped to crimp the flange or lip 30 over the edge of the screen, so as to clamp the screen and at the same time flatten the screen, so as topresent a fiat surface to the outer wall of the core or the inner wall of the mold, as the case may be.

In the past it has been common practice to insert brass diaphragrns, having apertures therein to permit the escape of the air, but prevent the escape of the sand. It seems that brass corrodes and that sand adheres to the corroded surface. The sand adhering thereto clogs the pores. It has been found that Monel metal does not have such an affinity for sand and therefore upon the removal of the core box or forms, the Monel screen may be removed with the walls of the forms without any sand adhering thereto.

In addition to the above features, Monel screen, or for that matter, any type of screen has a considerable area thereof available for the escape of air. This depends upon the mesh of the screen and the size of wire used. For some types of sand 30% of the screen area is available for the escape of air. This, however, varies greatly.

Instead of Monel metal, stainless steel or other metals or materials which do not have an aifinity for sand when used as air escapes for molds, may be used Within the purview of this invention.

Instead of holding the screen in position by a crimped lip or edge, the edge of the screen may be fused or soldered in position so as to hold the screen in a fixed relation with respect to the cylindrical supporting member. This, however, requires extremely accurate workmanship, as any solder flowing over the portions of the screen fills the mesh, so that it is necessary to confine the soldering operation exclusively to the margins of the screen.

Referring to the disclosure shown in Fig. 3, a. pair of wires or suitable reenforcing members 40 are placed on the underside of the screen 24 so as to provide a support for the screen. In Fig. 3 only one of these members 40 has been shown, as the other member extends parallel to the one shown but is located in the cut away portion. Instead of two, any suitable number of reenforcing members may be used. In some types of structures where the diameter of the cylindrical shell 26 and the screen 24 is small no reenforcing members are required. However, when the diameter gets larger it is at times quite desirable to reenforce the screen 24 by members 40. Instead of using reenforcing members as shown, any other type of suitable reenforcing structures may be used so as to support the screen 24 to prevent it from bulging.

When to use reenforcing members 4!] depends entirely upon the requirements of the structure and the materials used. If the material of the screen 24 is sufficiently rigid to withstand the pressures of the materials used for making the core or the mold, the reenforcing members 40 are not needed. On the other hand, when there is danger of failure of member 24, either partially or entirely, it is then desirable to use reenforcing members 40. Mold, as used in the claim, is used to include a core box.

Although the preferred modification of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts which generally stated consist in a device capable of carrying out the objects set forth, in the novel parts, combination of parts and mode of operation, as disclosed and defined in the appended claim.

Having thus described my invention, I claim:

An air escape unit for use in forming structures from a granular substance supplied under pressure to a mold having an air escape hole drilled through a wall thereof, said unit including a cylindrical member having a uniform outer diameter provided with an annular groove adjacent one end thereof surrounded by a lip, and an annular screen member of noncorrosive material extending across the end of the cylindrical member so as to be seated in the annular groove and held in position by the lip crimped over the edge of the screen, which screen is positioned flush with the molding surface of the mold.

CARL R. SILER. 

